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oai:www.ideals.illinois.edu:2142/20514 2023-07-10 col_2142_5131 col_2142_14789 com_2142_5130 com_2142_14788 com_2142_8903

Denmark, Scott E. Dorow, Roberta L. 2011-05-07T12:41:23Z 2011-05-07T12:41:23Z 10000-01-01 1990 The stereochemical course of carbon migration from phosphorus to nitrogen and oxygen were investigated. Optically active ($\geq$99.9% e.e.) phosphonic and phosphinic azides were prepared and photolyzed in methanol to effect the phosphorus analogues of the carbonyl-Curtius rearrangement. These studies showed that carbon migration in the phosphinoyl-Curtius rearrangement proceeds with 99% net retention of configuration while the migration in the first example of the phosphonoyl-Curtius rearrangement occurs with 99.4% net retention of configuration. The stereoselectivity in the alkylation reactions of various chiral phosphorus-stabilized benzylic carbanions was also examined. Both racemic and scalemic 2-benzyl-1,3,2-oxazaphosphorinane-2-oxides were employed. The effects of solvent, base, additive, and electrophile were studied. The diastereoselectivity of alkylation is dependent on the phosphorus-stabilized carbanion which is used, but high diastereoselectivity (98:2-95:5) was realized. Multinuclear NMR spectroscopy was used to gain insight into the solution state structure of both symmetrical and unsymmetrical heterocyclic phosphorus-stabilized benzylic carbanions. The spectral data is consistent with a charge-alternating structure that has a planar anionic carbon. Information about the conformation of the anion as well as the ring form was obtained. Much information about the structure of phosphorus-stabilized carbanions was obtained through X-ray crystallographic studies of the first lithiated phosphonoyl-stabilized carbanion. Made available in DSpace on 2011-05-07T12:41:23Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9026171.pdf: 12647391 bytes, checksum: c3d7dbe1fa46a38ca8a277b09df55c56 (MD5) Previous issue date: 1990 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:44:24Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:19:32-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9026171 (UMI)AAI9026171 http://hdl.handle.net/2142/20514 eng Copyright 1990 Dorow, Roberta L. Chemistry, Organic Stereoselective alkylations and rearrangements of chiral phosphonic and phosphinic acid derivatives text Chemistry Chemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.